The rules seek to capture or destroy volatile organic chemicals — such as benzene, a known carcinogen — from the drilling and fracking of new wells, the EPA said.

In Colorado, the impact of the rules look to be limited as the state already regulates oil and gas emissions, but they could bring some additional controls to the Western Slope, environmentalists and state regulators said.

“The EPA took a hard look at the Colorado rules in putting the rule together,” said Bruce Baizell, a Durango-based staff attorney for the environmental group Earthworks. “They are generally similar.”

Kathleen Sgamma, vice president for government affairs at the Western Energy Alliance, a trade group, said the fact that the EPA and the Colorado rules are so similar shows that air regulation should be left with the states.

“It is just another example of the federal government usurping state authority,” Sgamma said.

But the air rules in Colorado have focused on the Front Range as part of efforts to cut ozone pollution.

The state already is requiring oil and gas companies in the region capture 95 percent of the leaks and fugitive emissions from plants, compressors and pipes.

On the Western Slope, there are some emission controls, but not as tight as they are on the Front Range, said Gary Kaufman, deputy director of the state’s Air Pollution Control Division.

“There are controls on condensate tanks, dehydrators and engines, but we will have to review the EPA rule to see if there is more” the state has to do, Kaufman said.

Earthworks’ Baizell said, “the Piceance Basin could see some benefits.”

The state oil and gas rules also require “green completions,” which are designed to capture emissions involved in fracking and finishing a well.

Operators in some cases can apply for a waiver from the rule, said Thomas Kerr, acting commission director.

In hydrofracturing large quantities of fluid — ranging from a few hundred thousand to millions of gallons — are pumped into a well under pressure to fracture the rock and release more oil and gas.

As the fluids flow back to the surface, they can carry with them large volumes of gases.

Elevated levels of potentially hazardous chemicals were found in the air during flow back near Battlement Mesa, a Garfield County residential development, in a study by the University of Colorado-Denver School of Public Health.

The federal green completion rule would cut emissions at 13,000 new and refracked wells each year by 95 percent, according to agency officials.

The new rules also require:

■ Reducing leaks from compressors and tanks

■ Leak detection and repairs at gas-processing plants

■ Reducing emissions form engines

When asked at a tele-press conference whether the new rules would work, Gina McCarthy, assistant administrator in the EPA Office of Air and Radiation, pointed to the ongoing efforts in Colorado and Wyoming.

“The states of Colorado and Wyoming have already chosen to regulate this industry,” she said.